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Phase Modulated Code

IP.com Disclosure Number: IPCOM000078797D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chapman, DW: AUTHOR

Abstract

A ternary data code, which attains high-track density and high-data rates, employs phase modulation of NRZI (PMNRZI) data, in which a "0" is represented by no transition, a "1" as a positive-going transition, and a "2" as a negative-going transition. Two clock periods for each ternary digit are used, in order to allow consecutive 1's or consecutive 2's. Data transitions are detected during even clock periods, and clock transitions are detected during odd clock periods.

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Phase Modulated Code

A ternary data code, which attains high-track density and high-data rates, employs phase modulation of NRZI (PMNRZI) data, in which a "0" is represented by no transition, a "1" as a positive-going transition, and a "2" as a negative-going transition. Two clock periods for each ternary digit are used, in order to allow consecutive 1's or consecutive 2's. Data transitions are detected during even clock periods, and clock transitions are detected during odd clock periods.

Every three NRZI type bits are contained in two PMNRZI digits. However, four transition cells are needed for two PMNRZI digits.

By buffering four bits in the encoder and looking ahead, a decision is made whether or not to insert a transition in some clock cells, as required to record consecutive 1's or consecutive 2's, and to limit the number of consecutive transition cells without a transition to no more than two.

Translation of NRZI binary data to PMHRZI ternary digits is made as follows: NRZI PMNRZI

000 00

001 01

010 02

011 10

100 11

101 12

110 20

111 21 000 22 (22=possible alternative to 00).

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